Preparation of secondary alcohols



V Patented Dec. 5, 1933 PREPARATION OF SECONDARY ALCOHOLS William Engs and Richard Z. Moravec, Berkeley,

Caliii, assignors to Shell Development Company, SanFrancisco, Calif., a corporation of Delaware No Drawing.

Application August 31, 1931 Serial No. 560,508

Claims- (Cl. 260-456) This invention relates to a process for the preparation of secondary alcohols from olefinic mixtures and is more particularly concerned with a process wherein highly reactive olefines are 5 rendered relatively inactive prior to the esterification of the less reactive olefines present without substantially sacrificing the yield of the latter reaction product.

Prior investigators have utilized olefine-conm taining fluids, such as those derived by the pyrogenetic treatment of peat, coal, oil shales and like carboniferous natural-materials to produce secondary alcohols but very few have been concerned with the proper treatment of highly re- 315' active unsaturates prior to the formation of the desirable secondary alcohols. Earlier workers have either employed an acid of. such strength and under predetermined conditions that the highly reactive unsaturates have been completegg ly polymerized while the less reactive unsaturates have been only partly esterified, thus decreasing the possible effective yield of secondary alcohol upon hydrolysis or have first polymerized and removed the highly reactive unsaturates prior to the esteriflcation of 'the less reactive unsaturates. In the first situation, the strength of acid employed was in the nature of a compromise; it was strong enough at the particular operating temperature to completely polymerize the highly reactive unsaturates, such as dioleflnes and tertiary-base olefines (olefines capable of yielding tertiary alcohols upon hydrolysis) without permitting such a rapid and excessive rise in temperature as to cause the substantial polymerization of the less reactive unsaturates such as secondary-base olefines (o lefines capable of yielding secondary alcohols upon hydrolysis). Accordingly, theacid was never strong enough at the particular operating temperature to convert substantially all of the secondary-base olefines to theircorresponding esters. The yield of the latter'wassacrificed due to thermal conditions. In the second situation, resort was had to the removal of the poly- 5 merized highly reactive unsaturates prior to the esterification of the secondary-base olefines as it was believed that otherwise the process could not be successfully operated, thus necessitating an operation which is dispensed with in our process. U

We have discovered that secondary alcohols can be prepared simply and economically from olefine-containing fiuids of the type mentioned heretofore by properly controlling the polymerization of the highly reactive unsaturates and subsequently esterifying the secondary-base olefines in the presence of the polymers.

The preferred initial material is substantially stripped of hydrocarbons containing less than four carbon atoms to the molecule and suitably 0 fractionated into fractions containing hydrocarbons of the same number of carbon atoms to the molecule. In certain instances, it will be difiicult to remove traces of higher and lower carbon compounds, but their presence is not detrimental to our process. In certain other situations, it may be desirable to operate with a fraction containing a mixture of carbon compounds-such as a 4 and 5 carbon compound fraction. We prefer to practice our process with a substantially pure fraction of hydrocarbons of which each molecule contains the same number of carbon atoms to the molecule. In segregating the hydrocarbons into suitable fractions, it will be found practically impossible to separate the parafiin hydrocarbons from the olefine hydrocarbons possessing the same number of carbon atoms to the molecule without uneconomical and complicated procedures. As the paraffin hydrocarbons may be considered as inert compounds in our process, their presence in their corresponding carbon compound fraction is not accompanied by any detrimental effect.

' 'Ifhe fractions to be treated are thus characteristically composed of paraffin hydrocarbons, s5 olefines, both iscand normal, which yield secondary derivatives (hereinafter designated as secondary-base olefines), iso-olefines which yield tertiary derivatives (hereinafter designated as tertiary-base olefines) and traces of diolefines such as butadiene and isoprene.

For illustrative purposes only, reference will be had to a substantially pure B-B fraction which represents a mixture of butane and butene obtained by, distillation or condensation or both.

' Besides the butane there will be normally present organic acids as benzene sulfonic acids or the sulfonic acids of the homologues of benzene.

The desired fraction in the liquid state is contacted with the polymerizing agent in any suitable manner, with or without pressure. For example, resort may be hadto the agitation of the of throughput of the olefine-containing fluid.

With'stronger acids, lower temperatures in the reactor must prevail and/or the rate of throughput should be greater whereas with relatively weak acids, higher temperatures may be maintained in the reactor with or without a decreased rate of throughput. The rate of throughput and the strength of acid employed are adjusted according to the character and quantity of the tertiary-base olefine and the temperature of the process so that negligible esterification andpolymerization of secondary-base olefines occur. In practicing our invention, we preferably employ 60% to 70% HzSO-i as it apparently yields the best results with butane-butene and pentanepentene fractions, which contain secondary amylenes, trimethyl ethylene and/or other tertiary amylene, or the like. The rate of through-' put of the butane-butene fraction is about 0.6 gallons/minute/gallon reaction space when the isobutylene content is about 18% by weight employing 70% H2804. the acid under the above conditions is 0.3 gallons/minute/gallon reaction space. The reaction temperature is maintained in the above example at 122 F. and it has been found necessary to supply heat to the reaction. It is to be understood that as stronger acids are employed, the rates of throughput of the reactants are either decreased or the reaction temperature maintained below 122 F. The converse is true with weaker acids. With fractions containing hydrocarbons containing different numbers of carbon atoms to the molecule, the heavier molecular fractions are more sensitive to the action of acid and consequently the conditions preferable with a butane-butene fraction are too strenuous for a pentane-pentene fraction and modifications apparent to the chemist are necessary.

The isobutylene polymerizes under the conditions of the process whereas butene-1 and butene-2 substantially. do not and the former is associated with the butane and isobutane (parafin hydrocarbons), if any is present. Any dioleflne present in the fraction undergoing treatment is polymerized practically simultaneousl with the is'obutylene.

In certain instances, as above, an input of heat is necessary to maintain the proper reaction temperature although with stronger acids and/or slower rates of throughput, the reactants may be brought together without any external application of heat due to the exothermic heat of reaction. In the latter situation no cooling is necessary during the polymerization stage as the potential temperature rise above the maximum re action temperature may be compensated for by adjustment of the rate of throughput of the olefine-containing fluid and/or acid. 7

The fluid containing polymers and free secondary butene as well as butane and possibly isobutane is introduced into a'reactor wherein it is contacted with 90% to 100% H2SO4 at a tempera- The rate of throughput of haps a dior tri-isobutylene hydrogen sulfate but this may be taken 'care of by maintaining a slight excess of acid in the second reactor.

Where substantially one molecule of acid has been employed for each molecule of butene, the reaction progresses in the direction of butyl hydrogen sulfate. The liquid mixture in the vessel separates into two liquid phases, the upper layer comprising essentially butane and the lower layer butyl hydrogen sulfate. Any dibutyl sulfate, if formed, is found dissolved in both layers. The isobutylene polymers will collect with the butane. The lower layer is separated from the upper layer by any convenient mode and is then hydrolyzed with an aqueous medium such as water, aqueous alcohol, preferably secondary alcohol, and the like so that the diluted liquid has an acidity of 10% to 15%. The amount of dibutyl sulfate in the lower layer is quite small and forms a layer on the surface of the dilute acid product which layer is removed in any suitable manner and subsequently converted to secondary butyl alcohol as by dis- I tillation with weak acid, aqueous or acid solutions of alcohols, preferably of secondary alcohols, alkyl hydrogen sulfate solution or with water (either in the presence or absence of a suitable emulsifying agent) Any di-or tri-isobutylene hydrogen sulfate, if formed earlier in the process, will revert back to the original polymer or some higher polymer and can be easily separated from the butyl hydrogen sulfate due to the differences in specific gravity. The dior tri-isobutylene hydrogen sulfate may form a certain amount of alcohol on dilution which will be retained in the acid solution of butyl hydrogen sulfate. This is not detrimental in view of the following: The acid solution is diluted to an acidity of about 15% and heated to liberate the secondary butyl alcohol While we have in the foregoing described insome detailthe preferred embodiment of our invention and some variants thereof, it will be understood that this is only for the purpose of making the invention more clear and that the invention is not to be regarded as limited to the details of operation described, nor is it dependent upon the soundness or accuracy of the theories which we have advanced as to the reasons for the advantageous results attained. On the other hand, the invention is toibe regarded as limited only by the terms of the accompanying claims, in which it is our intention to claim all novelty inherent therein as broadly as is possible. in view of the prior art.

We claim as our invention:

1. A method of producing secondary alcohols from a mixture of olefines in the liquid state,

comprising: polymerizing tertiary hase olefines, which are present, without the substantial conversion of secondary-base olefines,'treating the resulting liquid mixture with a polybasic inorganic acid of a strength and at a temperature at which substantial esterification of the secondary base olefines is efi'ected and hydrolyzing the resulting esters. W 2.A.,method of producing secondary alcohols from a mixture of olefines in the liquid state, comprising: polymerizing tertiary-base olefines, which are present, without the substantial conversion of secondary-base olefines, treating the resulting liquid mixture with H2804 of a strength and at a temperature at which substantial esterification of the secondary-base olefines is-effected and hydrolyzing the resulting esters.

4. A method of producing secondary alcohols from a mixture of olefines in the liquid state, comprising: polymerizing tertiary-base olefines,

I which are present, without the substantial conversion of secondary-base olefines, treating the resulting liquid mixture with a polybasic inorganic acid of a strength and at a temperature at which substantial esterification of the secondarybase olefines is effected, removing the polymers from the esters formed and hydrolyzing the latter.

'5. A method of producing secondary alcohols from a mixture of olefines in the liquid state, comprising: polymerizing tertiary-base olefines, which are present, without the substantial conversion of secondary-base olefines, treating the resulting mixture with H2804 of a strength and at a temperature at which substantial esterification of the secondary-base olefines is effected, removing the polymers from the esters formed and hydrolyzing the latter.

6. A method of producing secondary alcohols from a mixture of olefine and. paraflin hydrocarbons in the liquid state, comprising: polymerizing tertiary-base olefines, which are present, without the substantial conversion of secondarybase olefines, treating the resulting liquid mixture with a polybasic inorganic acid of a strength and at a temperature at which substantial esterification of the secondary-base olefines is effected, separating the esters formed from the mixture and hydrolyzing the former.

7. A method of producing secondary alcohols from a mixture of olefine and parafiin hydrocarbons in the liquid state, comprising: polymerizfrom a mixture of olefine and paraffin hydrocarbons in the liquid state, comprising: polymerizing tertiary-base olefines, which 'are present, without the substantial conversion ofsecondarybase olefines, treating the resultingliquid mixture with about 90% to about 100% 1-1250; at a temperature at which substantial esterification of the secondary-base olefines is efiected, separating the esters formed from the mixture and hydrolyzing the former.

9. A method of producing secondary alcohols from a liquid hydrocarbon fraction which contains olefine hydrocarbons containing more than three carbon atoms to the molecule, comprising: polymerizing tertiary-base olefines, which are present, without thesubstantial conversion of secondary-base olefines, treating the resulting liquid mixturewith a polybasic inorganic acid of a strength and at a temperature at which substantial esterification of the secondary-base olefines is efiected, separating the esters formed from the mixture and hydrolyzing the former.

10. A method of producing secondary alcohols I from a liquid hydrocarbon fraction which contains olefine hydrocarbons containing more than three carbon atoms to the molecule, comprising? polymerizing tertiary-base olefines, which are present, without the substantial conversion of secondary-base olefines, treating the resulting liquid mixture with H2504 of a strength and at a temperature at which substantial esterification of the secondary-base olefinesiseffected,separating the esters formed from the mixture and by:

drolyzing the former.

11. A method of producing secondary alcohols from a liquid hydrocarbon fraction which contains olefine hydrocarbons containing more than three carbon atoms to the molecule, comprising: polymerizing tertiary-base olefines, which are present, without the substantial conversion of secondary-base olefines, treating the resulting liquid mixture with about to about 100% H2804 at a temperature at which substantial esterification of the secondary-base olefines is effected, separating the esters formed from the mixture and hydrolyzing the former.

12. A method of producing secondary butanol from liquid hydrocarbon mixtures containing butylene and isobutylene, comprising: polymerizing the isobutylene without the substantial conversion of the butylene, treating the. resulting liquid mixture with a polybasic inorganic acid of a strength and at a temperature at which substantial esterification of the butylene is efiected, separating the esters formed from the mixture and hydrolyzing the former.

13. A method of producing secondary butanol from liquid hydrocarbon mixtures containing butylene and isobutylene, comprising: polymerizing the isobutylene without the substantial conversion of the butylene, treating'theresulting liquid mixture with H2804 of a strength and at a temperature at which substantial esterificationof the butylene is effected, separating the esters formed from the mixture and hydrolyzing the former.

14. A method of producing secondary butanol from liquid hydrocarbon mixtures containing butylene and isobutylene, comprising: polymerizing the isobutylene without the substantial conversion of the butylene, treating the resulting liquid mixture with about 90% to about 100% H2804 at a temperature at which substantial esterification of the butylene is effected, separating the esters formed from the mixture. and hydrolyzing the former.

1-5. A method of producing secondary pentanol from liquid hydrocarbon mixtures containing 'amylene and trimethyl ethylene, comprising: polymerizing the trimethyl ethylene without the substantial conversion of the 'amylene, treating the resulting liquid mixture with a polybasic in- 16. A method of producing secondary pentanol from liquid hydrocarbon mixtures containing amylene and trimethyl ethylene, comprising: polymerizingthe trimethyl ethylene without the substantial conversion of the amylene, treating the resulting liquid mixture with H2804 of a strength and at a temperature at which substantial esteriflcation of the amylene is effected, separating the esters formed from the mixture and hydrolyzing the former.

17. A niethod of producing secondary pentanol from liquid hydrocarbon mixtures containing amylene and trimethyl ethylene, comprising: polymerizing the trimethyl ethylene without the substantial conversion of the amylene, treating the resulting liquid mixture with about 90% to about 100% H2804 at a temperature at which substantial esterification of the amylene is effected, separating the esters formed from the mixture and hydrolyzing the former.

18. In a method of producing secondary alcohols from a mixture of olefines in the liquid state, the steps comprising: polymerizing tertiary-base olefines, which are present, without the substantial conversion of secondary base olefines, and

treating the resulting liquid mixture with an in-- organic acid of a strength and at a temperature 'at which substantial esterification of the secondary base olefines is effected.

19. In a method of producing secondary alcohols from a mixture of olefines in the liquid state, the steps comprising: polymerizing tertiary-base olefines, which are present, without the substantial conversion of secondary base olefines, and treating the resulting liquid mixture with a polybasic inorganic acid of a strength and at a temperature at which substantial esteri-fication of the secondary base olefines is effected.

20. In a method'of producing secondary alcohols from a mixture of olefines in the liquid state, the steps comprising: polymerizing tertiary-base olefines, which are present, without the substantial conversion of secondary base olefines, and treating the resulting liquid mixture with H2804 of a strength and at a temperature at which substantial esteriflcation of the secondary base olefines is efiected.

WILLIAM ENGS. RICHARD Z. MORAVEC. 

